Encoders have been widely used in many industries for measuring either the linear or rotary movement of objects. A rotary encoder is normally used to covert the angular position or rotary movement of a shaft to an analog or digital signal. A typical rotary encoder may comprise an encoding means and a sensor connected to a rotary device for converting the rotational movement of the rotary device to an electronic signal. For example, a rotary encoder may be connected to the shaft of a motor to convert the angular position of the shaft of a motor to either an analog or a digital signal. Rotary encoders are typically used in applications that require precise rotational measurements, for example, a computer numeric control (CNC) machine, a robotics system, a motorized radar platform, or photographic lenses. Optical and magnetic rotary encoders are two of the most common encoders available in the market. However other types of encoders, such as inductive encoder, capacitive encoder and eddy current encoder are also widely used in many applications for measuring both linear and rotary movements of objects.
Typically, a rotary encoder may include an encoding means that is rotatable with a shaft and a sensor that are mounted in a housing of the encoder. In order to achieve an accurate measurement, the encoding means and the sensor need to be aligned with respect to their relative axial and radial positions. Therefore, in practice, it is necessary to radially align the encoder means with respect to the shaft so that the rotation axis of the shaft is coaxial with the center of the encoding means. In addition, it may also be necessary to align the relative axial position between the encoding means and the sensor by adjusting the gap between the two components. Therefore, in order to achieve an accurate measurement, it is important that the encoder disk and the sensor are aligned accurately during installation. In some instances, the encoders may be pre-aligned by the manufacturer prior to shipment to customers. It is important to include a locking mechanism in such an encoder system, in order to retain the pre-aligned settings made by the manufacturer. The locking mechanism may also prevent the pre-aligned settings from being damaged during shipping and handling or while being installed.
There are many conventional alignment methods that may be implemented in an encoder to adjust the alignment of the encoding means and the sensor, these methods generally involve modification of either the encoder housing or the hub. Other methods may include additional alignment components or features being attached to either the encoder housing or the hub, resulting in a complex system design, complex manufacturing steps, an increase in the number of component parts, and higher encoder cost. Alternatively, an external alignment jig with a gaping device may be utilized to align the encoding means and the sensor. However, such methods may involve a complex installation process for the end user. Additionally, other conventional alignment methods may require the use of an assembly kit with a special tool. However, such methods may require the end user to implement costly and time consuming installation steps, and therefore, may not be acceptable for a compact modular encoder system.
Accordingly, it would be desirable to provide an encoder module having a simple and effective alignment system that can be implemented by an end user easily and inexpensively, while maintaining high encoder reliability and robustness.